Never load from hear say information. Especially while you are learning the ropes I.E. reading pressure. If anyone suggests powders or loads that are not in a manual stay away. Hodgen has a nice manual as due all the major bullet Mfgs, Years ago the Speer manual had an article on loads and reading pressures that was written by Jack OConner and it should be on your must read list. I think it was manual #10? Lyman at one time had the finest loading manual printed but all of my stuff is dated now about 10 years old.
All that being said, the vast majority of the time the powder that gives the velocity you want at safe pressures and fills the case to the bottom of the neck will be ideal, or very close to it. In general terms powders that work well in 223 are usually at least decent in the 308. The 30-30 is kinda out by it self being as it is loaded to very low pressures by comparison. Some rifle powders don"t like 30-30 operating pressures and are very erratic in it. Have fun and be safe.